1. Technical Field
The present invention relates to liquid containers having decompressed spaces for absorbing gas dissolved in liquid stored in the liquid containers, relates to methods for producing the liquid containers, and relates to ink-jet recording apparatuses using the liquid containers as ink packs.
2. Related Art
Typical, known liquid-consuming apparatuses include liquid-ejecting apparatuses that eject droplets from ejecting-heads. Typical liquid-ejecting apparatuses include ink-jet recording apparatuses that have ink-jet recording heads for recording images. Ink-jet recording apparatuses are widely used for printing including color printing. This popularity may be due to the relatively small amount of noise they produce during printing, and to their ability to produce small dots in high density.
In some liquid-consuming apparatuses, such as many ink-jet recording apparatuses, liquid is supplied to the liquid-consuming apparatuses from liquid containers that store liquid for use by the liquid-consuming apparatuses. In such arrangements, the liquid containers may be in the form of cartridges, detachable from the liquid-consuming apparatuses, and easily replaced by users when the liquid inside the liquid containers is exhausted.
In general, ink-jet recording apparatuses often include carriages having attached recording heads that discharge ink droplets and that reciprocate along recording surfaces of recording media. In some methods of supplying ink from ink cartridges to the recording heads, the ink cartridges are attached to the carriages, and ink is supplied to the recording heads from the ink cartridges, which reciprocate together with the recording heads. On the other hand, in some methods of supplying ink, the ink cartridges are attached to casings or the like of the apparatus bodies, and ink is supplied from the ink cartridges to the recording heads via ink channels formed of flexible tubes or the like.
When ink cartridges filled with ink are left to stand for a long period of time, N2 is sometimes generated by chemical changes of pigments in the ink. Moreover, N2, O2, and the like can enter from outside through walls of the ink containers such as cartridges when they have a poor gas-barrier property.
If printing is performed, and large amounts of N2 and O2 are dissolved in the ink inside the ink cartridges, bubbles can be generated in the ink due to pressure changes during ink discharge and the like. Such bubbles can block the ink channels, and can cause discharge failure. This degrades printing quality.
To solve the above-described problems, an ink cartridge having the structure shown in FIG. 6 has been already proposed. An ink cartridge 101 described in JP-A-2005-169851 includes an ink pack (liquid container) 102 that stores ink and a rigid case 150 that accommodates the ink pack 102. The case 150 includes an open-top case body 150A and a cover 150B sealing the top opening of the case body 150A. Moreover, there is a circuit board 151 including an integrated circuit (IC) such as a semiconductor storage cell for storing information such as ink types, ink levels, and the like, disposed at a side surface of the case 150.
The ink pack 102 includes a liquid-containing bag (container body) 103 formed of a flexible-film bag for storing ink, an ink-supplying section (liquid-supplying section) 104 connected to an end of the liquid-containing bag 103 and having an ink-supply port (liquid-supply port) for supplying ink from the liquid-containing bag 103 to a recording apparatus, and a gas-absorbing device 105 for absorbing gases such as N2 and O2 dissolved in the ink stored inside the liquid-containing bag 103. The supply port of the ink-supplying section 104 is sealed with a supply-port film 40 before the ink pack 102 is used.
As shown in FIG. 7, a spring 106 and a valve element 107 urged by the spring 106 are disposed inside the ink-supplying section 104 at an outer end portion of the ink-supplying section 104, and a seal 108 is attached to the outer end of the ink-supplying section 104. Moreover, a valve element 109 is disposed inside the ink-supplying section 104 at an inner end portion of the ink-supplying section 104, and a check-valve cover 110 is attached to the inner end of the ink-supplying section 104. The check-valve cover 110 is formed separately from the ink-supplying section 104, and is integrated afterward with the ink-supplying section 104, using thermal caulking.
The spring 106, the valve element 107, and the seal 108 function as an on-off valve that opens a flow channel only when predetermined flow-channel means is connected to the supply port. The valve element 109 and the check-valve cover 110 constitutes a check valve 117 that opens the flow channel only when the liquid flows in a direction from the liquid-containing bag 103 to the outside.
As shown in FIG. 7, the gas-absorbing device 105 includes a decompressed container 112 having an opening 111 at an end thereof, and a flexible film 113 that closes the opening 111 while the interior of the decompressed container 112 is decompressed. With this, the interior of the decompressed container 112 is defined as a decompressed space 105a for absorbing gases such as N2 and O2 dissolved in the ink. This gas-absorbing device 105 is formed separately from the liquid-containing bag 103 and the ink-supplying section 104, and is connected to the ink-supplying section 104 by fitting claws 115 formed at the inner end of the ink-supplying section 104 into catching portions 116 formed at the end of the decompressed container 112. The gas-absorbing device 105 is then disposed inside the liquid-containing bag 103.
This gas-absorbing device 105 receives the pressure inside the decompressed space 105a using the inner surfaces thereof, and at the same time, at least part of partition walls of the outer surfaces of the gas-absorbing device 105 (the partition walls being in contact with the ink inside the liquid-containing bag 103) is composed of a gas-permeable material through which gases dissolved in the ink inside the liquid-containing bag 103 can permeate.
Due to the decompressed space 105a, which is brought into contact with the ink inside the ink pack 102 as described above, for example, gases permeating from outside through the liquid-containing bag 103 and dissolved in the ink can be collected in the decompressed space 105a. This can prevent problems such as discharge failure caused by bubbles dissolved in the ink.
However, in the above-described ink pack 102, the decompressed space 105a for removing gases dissolved in the ink is provided by the gas-absorbing device 105, which is an independent and dedicated component. This leads to an increase in the number of parts, an additional assembling process for connecting the gas-absorbing device 105 to the ink-supplying section 104, and thus an increase in the cost of the ink pack 102. Moreover, the catching portions 116 and the claws 115 for connecting the ink-supplying section 104 and the gas-absorbing device 105 result in the structures of these components becoming more complex. Furthermore, according to a method of producing the above-described ink pack 102, for example, the opening of the decompressed container 112 is sealed with the flexible film 113 under a dedicated vacuum environment. After the gas-absorbing device 105 having the decompressed space 105a is formed, the gas-absorbing device 105 and the ink-supplying section 104 are assembled together, and then the gas-absorbing device 105 is fitted into the liquid-containing bag 103. Through these steps, the final structure having the decompressed space 105a sealed inside the liquid-containing bag 103 is formed. However, when the decompressed space 105a is exposed under an atmospheric-pressure environment before the final structure is formed, gases in the air can be absorbed in the decompressed space 105a, thereby causing a deterioration in the gas-absorption performance of the decompressed space 105a. 